1. Field of the Invention
The present invention relates to a light source device, a video projector and a video projection method, which are adaptable for a digital light processing (DLP (registered trade mark)) type data projector (video projector).
2. Description of the Related Art
Displaying a color image with a projection type display apparatus requires planar light sources which emit respective primary R, G and B light, and corresponding spatial light modulators, which may result in an increased number of parts and difficulty in achieving smallness, lightness and inexpensiveness of the entire apparatus. For the purpose of solving such a problem, a system has been proposed, in which a light emitting diode emitting ultraviolet light is used for the light source, and a visible light reflection film having characteristics that the ultraviolet light is transmitted and visible light is reflected is formed on the surface of a color wheel On which the ultraviolet light from the light, emitting diode is irradiated, on the light source side, and fluorescent layers respectively emitting visible light corresponding to R, G and B by the irradiation of the ultraviolet light are formed on the back surface of the color wheel. An example of such system is disclosed in JP-A-2004-341105.
However, if the above-described system is employed in practice, various red fluorescent materials, which are currently known in the art, are lacking in red luminance since their emission efficiency is remarkably lower than that of other green and blue fluorescent materials.
As a result, when a bright projection image is to be obtained by preferring luminance, there arises a problem of white balance collapse and hence low color reproducibility. On the other hand, when the white balance and hence the color reproducibility are emphasized, the entire luminance is lowered to meet a red image having a low luminance, which results in a dark image.